gdb/microblaze-tdep.c

   1 /* Target-dependent code for Xilinx MicroBlaze.
   2
   3    Copyright 2009 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include "defs.h"
  21 #include "arch-utils.h"
  22 #include "dis-asm.h"
  23 #include "frame.h"
  24 #include "trad-frame.h"
  25 #include "symtab.h"
  26 #include "value.h"
  27 #include "gdbcmd.h"
  28 #include "breakpoint.h"
  29 #include "inferior.h"
  30 #include "regcache.h"
  31 #include "target.h"
  32 #include "frame.h"
  33 #include "frame-base.h"
  34 #include "frame-unwind.h"
  35 #include "dwarf2-frame.h"
  36 #include "osabi.h"
  37
  38 #include "gdb_assert.h"
  39 #include "gdb_string.h"
  40 #include "target-descriptions.h"
  41 #include "opcodes/microblaze-opcm.h"
  42 #include "opcodes/microblaze-dis.h"
  43 #include "microblaze-tdep.h"
  44 \f
  45 /* Instruction macros used for analyzing the prologue.  */
  46 /* This set of instruction macros need to be changed whenever the
  47    prologue generated by the compiler could have more instructions or
  48    different type of instructions.
  49    This set also needs to be verified if it is complete.  */
  50 #define IS_RETURN(op) (op == rtsd || op == rtid)
  51 #define IS_UPDATE_SP(op, rd, ra) \
  52         ((op == addik || op == addi) && rd == REG_SP && ra == REG_SP)
  53 #define IS_SPILL_SP(op, rd, ra) \
  54         ((op == swi || op == sw) && rd == REG_SP && ra == REG_SP)
  55 #define IS_SPILL_REG(op, rd, ra) \
  56         ((op == swi || op == sw) && rd != REG_SP && ra == REG_SP)
  57 #define IS_ALSO_SPILL_REG(op, rd, ra, rb) \
  58         ((op == swi || op == sw) && rd != REG_SP && ra == 0 && rb == REG_SP)
  59 #define IS_SETUP_FP(op, ra, rb) \
  60         ((op == add || op == addik || op == addk) && ra == REG_SP && rb == 0)
  61 #define IS_SPILL_REG_FP(op, rd, ra, fpregnum) \
  62         ((op == swi || op == sw) && rd != REG_SP && ra == fpregnum && ra != 0)
  63 #define IS_SAVE_HIDDEN_PTR(op, rd, ra, rb) \
  64         ((op == add || op == addik) && ra == MICROBLAZE_FIRST_ARGREG && rb == 0)
  65
  66 /* The registers of the Xilinx microblaze processor.  */
  67
  68 static const char *microblaze_register_names[] =
  69 {
  70   "r0",   "r1",  "r2",    "r3",   "r4",   "r5",   "r6",   "r7",
  71   "r8",   "r9",  "r10",   "r11",  "r12",  "r13",  "r14",  "r15",
  72   "r16",  "r17", "r18",   "r19",  "r20",  "r21",  "r22",  "r23",
  73   "r24",  "r25", "r26",   "r27",  "r28",  "r29",  "r30",  "r31",
  74   "rpc",  "rmsr", "rear", "resr", "rfsr", "rbtr",
  75   "rpvr0", "rpvr1", "rpvr2", "rpvr3", "rpvr4", "rpvr5", "rpvr6",
  76   "rpvr7", "rpvr8", "rpvr9", "rpvr10", "rpvr11",
  77   "redr", "rpid", "rzpr", "rtlbx", "rtlbsx", "rtlblo", "rtlbhi"
  78 };
  79
  80 #define MICROBLAZE_NUM_REGS ARRAY_SIZE (microblaze_register_names)
  81 \f
  82 static int microblaze_debug_flag = 0;
  83
  84 void
  85 microblaze_debug (const char *fmt, ...)
  86 {
  87   if (microblaze_debug_flag)
  88     {
  89        va_list args;
  90
  91        va_start (args, fmt);
  92        printf_unfiltered ("MICROBLAZE: ");
  93        vprintf_unfiltered (fmt, args);
  94        va_end (args);
  95     }
  96 }
  97 \f
  98 /* Return the name of register REGNUM.  */
  99
 100 static const char *
 101 microblaze_register_name (struct gdbarch *gdbarch, int regnum)
 102 {
 103   if (regnum >= 0 && regnum < MICROBLAZE_NUM_REGS)
 104     return microblaze_register_names[regnum];
 105   return NULL;
 106 }
 107
 108 static struct type *
 109 microblaze_register_type (struct gdbarch *gdbarch, int regnum)
 110 {
 111   if (regnum == MICROBLAZE_SP_REGNUM)
 112     return builtin_type (gdbarch)->builtin_data_ptr;
 113
 114   if (regnum == MICROBLAZE_PC_REGNUM)
 115     return builtin_type (gdbarch)->builtin_func_ptr;
 116
 117   return builtin_type (gdbarch)->builtin_int;
 118 }
 119
 120 \f
 121 /* Fetch the instruction at PC.  */
 122
 123 unsigned long
 124 microblaze_fetch_instruction (CORE_ADDR pc)
 125 {
 126   enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch);
 127   gdb_byte buf[4];
 128
 129   /* If we can't read the instruction at PC, return zero.  */
 130   if (target_read_memory (pc, buf, sizeof (buf)))
 131     return 0;
 132
 133   return extract_unsigned_integer (buf, 4, byte_order);
 134 }
 135 \f
 136
 137 static CORE_ADDR
 138 microblaze_push_dummy_code (struct gdbarch *gdbarch, CORE_ADDR sp,
 139                             CORE_ADDR funcaddr,
 140                             struct value **args, int nargs,
 141                             struct type *value_type,
 142                             CORE_ADDR *real_pc, CORE_ADDR *bp_addr,
 143                             struct regcache *regcache)
 144 {
 145   error (_("push_dummy_code not implemented"));
 146   return sp;
 147 }
 148
 149
 150 static CORE_ADDR
 151 microblaze_push_dummy_call (struct gdbarch *gdbarch, struct value *function,
 152                             struct regcache *regcache, CORE_ADDR bp_addr,
 153                             int nargs, struct value **args, CORE_ADDR sp,
 154                             int struct_return, CORE_ADDR struct_addr)
 155 {
 156   error (_("store_arguments not implemented"));
 157   return sp;
 158 }
 159
 160 static const gdb_byte *
 161 microblaze_breakpoint_from_pc (struct gdbarch *gdbarch, CORE_ADDR *pc,
 162                                int *len)
 163 {
 164   static gdb_byte break_insn[] = MICROBLAZE_BREAKPOINT;
 165
 166   *len = sizeof (break_insn);
 167   return break_insn;
 168 }
 169 \f
 170 /* Allocate and initialize a frame cache.  */
 171
 172 static struct microblaze_frame_cache *
 173 microblaze_alloc_frame_cache (void)
 174 {
 175   struct microblaze_frame_cache *cache;
 176   int i;
 177
 178   cache = FRAME_OBSTACK_ZALLOC (struct microblaze_frame_cache);
 179
 180   /* Base address.  */
 181   cache->base = 0;
 182   cache->pc = 0;
 183
 184   /* Frameless until proven otherwise.  */
 185   cache->frameless_p = 1;
 186
 187   return cache;
 188 }
 189
 190 /* The base of the current frame is actually in the stack pointer.
 191    This happens when there is no frame pointer (microblaze ABI does not
 192    require a frame pointer) or when we're stopped in the prologue or
 193    epilogue itself.  In these cases, microblaze_analyze_prologue will need
 194    to update fi->frame before returning or analyzing the register
 195    save instructions.  */
 196 #define MICROBLAZE_MY_FRAME_IN_SP 0x1
 197
 198 /* The base of the current frame is in a frame pointer register.
 199    This register is noted in frame_extra_info->fp_regnum.
 200
 201    Note that the existance of an FP might also indicate that the
 202    function has called alloca.  */
 203 #define MICROBLAZE_MY_FRAME_IN_FP 0x2
 204
 205 /* Function prologues on the Xilinx microblaze processors consist of:
 206
 207    - adjustments to the stack pointer (r1) (addi r1, r1, imm)
 208    - making a copy of r1 into another register (a "frame" pointer)
 209      (add r?, r1, r0)
 210    - store word/multiples that use r1 or the frame pointer as the
 211      base address (swi r?, r1, imm OR swi r?, fp, imm)
 212
 213    Note that microblaze really doesn't have a real frame pointer.
 214    Instead, the compiler may copy the SP into a register (usually
 215    r19) to act as an arg pointer.  For our target-dependent purposes,
 216    the frame info's "frame" member will be the beginning of the
 217    frame.  The SP could, in fact, point below this.
 218
 219    The prologue ends when an instruction fails to meet either of
 220    these criteria.  */
 221
 222 /* Analyze the prologue to determine where registers are saved,
 223    the end of the prologue, etc.  Return the address of the first line
 224    of "real" code (i.e., the end of the prologue). */
 225
 226 static CORE_ADDR
 227 microblaze_analyze_prologue (struct gdbarch *gdbarch, CORE_ADDR pc,
 228                              CORE_ADDR current_pc,
 229                              struct microblaze_frame_cache *cache)
 230 {
 231   char *name;
 232   CORE_ADDR func_addr, func_end, addr, stop, prologue_end_addr = 0;
 233   unsigned long insn;
 234   int rn, rd, ra, rb, imm;
 235   enum microblaze_instr op;
 236   int flags = 0;
 237   int save_hidden_pointer_found = 0;
 238   int non_stack_instruction_found = 0;
 239
 240   /* Find the start of this function. */
 241   find_pc_partial_function (pc, &name, &func_addr, &func_end);
 242   if (func_addr < pc)
 243     pc = func_addr;
 244
 245   if (current_pc < pc)
 246     return current_pc;
 247
 248    /* Initialize info about frame.  */
 249    cache->framesize = 0;
 250    cache->fp_regnum = MICROBLAZE_SP_REGNUM;
 251    cache->frameless_p = 1;
 252
 253   /* Start decoding the prologue.  We start by checking two special cases:
 254
 255      1. We're about to return
 256      2. We're at the first insn of the prologue.
 257
 258      If we're about to return, our frame has already been deallocated.
 259      If we are stopped at the first instruction of a prologue,
 260      then our frame has not yet been set up. */
 261
 262   /* Get the first insn from memory.  */
 263
 264   insn = microblaze_fetch_instruction (pc);
 265   op = microblaze_decode_insn (insn, &rd, &ra, &rb, &imm);
 266
 267   if (IS_RETURN(op))
 268     return pc;
 269
 270   /* Start at beginning of function and analyze until we get to the
 271      current pc, or the end of the function, whichever is first.  */
 272   stop = (current_pc < func_end ? current_pc : func_end);
 273
 274   microblaze_debug ("Scanning prologue: name=%s, func_addr=%s, stop=%s\n",
 275                     name, paddress (gdbarch, func_addr),
 276                     paddress (gdbarch, stop));
 277
 278   for (addr = func_addr; addr < stop; addr += INST_WORD_SIZE)
 279     {
 280       insn = microblaze_fetch_instruction (addr);
 281       op = microblaze_decode_insn (insn, &rd, &ra, &rb, &imm);
 282       microblaze_debug ("%s %08lx\n", paddress (gdbarch, pc), insn);
 283
 284       /* This code is very sensitive to what functions are present in the
 285          prologue.  It assumes that the (addi, addik, swi, sw) can be the
 286          only instructions in the prologue.  */
 287       if (IS_UPDATE_SP(op, rd, ra))
 288         {
 289           microblaze_debug ("got addi r1,r1,%d; contnuing\n", imm);
 290           if (cache->framesize)
 291             break;      /* break if framesize already computed.  */
 292           cache->framesize = -imm; /* stack grows towards low memory.  */
 293           cache->frameless_p = 0; /* Frame found.  */
 294           save_hidden_pointer_found = 0;
 295           non_stack_instruction_found = 0;
 296           continue;
 297         }
 298       else if (IS_SPILL_SP(op, rd, ra))
 299         {
 300           /* Spill stack pointer.  */
 301           cache->register_offsets[rd] = imm; /* SP spilled before updating.  */
 302
 303           microblaze_debug ("swi r1 r1 %d, continuing\n", imm);
 304           save_hidden_pointer_found = 0;
 305           if (!cache->framesize)
 306             non_stack_instruction_found = 0;
 307           continue;
 308         }
 309       else if (IS_SPILL_REG(op, rd, ra))
 310         {
 311           /* Spill register.  */
 312           cache->register_offsets[rd] = imm - cache->framesize;
 313
 314           microblaze_debug ("swi %d r1 %d, continuing\n", rd, imm);
 315           save_hidden_pointer_found = 0;
 316           if (!cache->framesize)
 317             non_stack_instruction_found = 0;
 318           continue;
 319         }
 320       else if (IS_ALSO_SPILL_REG(op, rd, ra, rb))
 321         {
 322           /* Spill register.  */
 323           cache->register_offsets[rd] = 0 - cache->framesize;
 324
 325           microblaze_debug ("sw %d r0 r1, continuing\n", rd);
 326           save_hidden_pointer_found = 0;
 327           if (!cache->framesize)
 328             non_stack_instruction_found = 0;
 329           continue;
 330         }
 331       else if (IS_SETUP_FP(op, ra, rb))
 332         {
 333           /* We have a frame pointer.  Note the register which is
 334              acting as the frame pointer. */
 335           flags |= MICROBLAZE_MY_FRAME_IN_FP;
 336           flags &= ~MICROBLAZE_MY_FRAME_IN_SP;
 337           cache->fp_regnum = rd;
 338           microblaze_debug ("Found a frame pointer: r%d\n", cache->fp_regnum);
 339           save_hidden_pointer_found = 0;
 340           if (!cache->framesize)
 341             non_stack_instruction_found = 0;
 342           continue;
 343         }
 344       else if (IS_SPILL_REG_FP(op, rd, ra, cache->fp_regnum))
 345         {
 346           /* reg spilled after updating.  */
 347           cache->register_offsets[rd] = imm - cache->framesize;
 348
 349           microblaze_debug ("swi %d %d %d, continuing\n", rd, ra, imm);
 350           save_hidden_pointer_found = 0;
 351           if (!cache->framesize)
 352             non_stack_instruction_found = 0;
 353           continue;
 354         }
 355       else if (IS_SAVE_HIDDEN_PTR(op, rd, ra, rb))
 356         {
 357           /* If the first argument is a hidden pointer to the area where the
 358              return structure is to be saved, then it is saved as part of the
 359              prologue.  */
 360
 361           microblaze_debug ("add %d %d %d, continuing\n", rd, ra, rb);
 362           save_hidden_pointer_found = 1;
 363           if (!cache->framesize)
 364             non_stack_instruction_found = 0;
 365           continue;
 366         }
 367
 368       /* As a result of the modification in the next step where we continue
 369          to analyze the prologue till we reach a control flow instruction,
 370          we need another variable to store when exactly a non-stack
 371          instruction was encountered, which is the current definition
 372          of a prologue.  */
 373       if (!non_stack_instruction_found)
 374         prologue_end_addr = addr;
 375       non_stack_instruction_found = 1;
 376
 377       /* When optimizations are enabled, it is not guaranteed that prologue
 378          instructions are not mixed in with other instructions from the
 379          program. Some programs show this behavior at -O2. This can be
 380          avoided by adding -fno-schedule-insns2 switch as of now (edk 8.1)
 381          In such cases, we scan the function until we see the first control
 382          instruction.  */
 383
 384       {
 385         unsigned op = (unsigned)insn >> 26;
 386
 387         /* continue if not control flow (branch, return).  */
 388         if (op != 0x26 && op != 0x27 && op != 0x2d && op != 0x2e && op != 0x2f)
 389           continue;
 390         else if (op == 0x2c)
 391           continue;    /* continue if imm.  */
 392       }
 393
 394       /* This is not a prologue insn, so stop here. */
 395       microblaze_debug ("insn is not a prologue insn -- ending scan\n");
 396       break;
 397     }
 398
 399   microblaze_debug ("done analyzing prologue\n");
 400   microblaze_debug ("prologue end = 0x%x\n", (int) addr);
 401
 402   /* If the last instruction was an add rd, r5, r0 then don't count it as
 403      part of the prologue.  */
 404   if (save_hidden_pointer_found)
 405     prologue_end_addr -= INST_WORD_SIZE;
 406
 407   return prologue_end_addr;
 408 }
 409
 410 static CORE_ADDR
 411 microblaze_unwind_pc (struct gdbarch *gdbarch, struct frame_info *next_frame)
 412 {
 413   gdb_byte buf[4];
 414   CORE_ADDR pc;
 415
 416   frame_unwind_register (next_frame, MICROBLAZE_PC_REGNUM, buf);
 417   pc = extract_typed_address (buf, builtin_type (gdbarch)->builtin_func_ptr);
 418   /* For sentinel frame, return address is actual PC.  For other frames,
 419      return address is pc+8.  This is a workaround because gcc does not
 420      generate correct return address in CIE.  */
 421   if (frame_relative_level (next_frame) >= 0)
 422     pc += 8;
 423   return pc;
 424 }
 425
 426 /* Return PC of first real instruction of the function starting at
 427    START_PC.  */
 428
 429 CORE_ADDR
 430 microblaze_skip_prologue (struct gdbarch *gdbarch, CORE_ADDR start_pc)
 431 {
 432   struct symtab_and_line sal;
 433   CORE_ADDR func_start, func_end, ostart_pc;
 434   struct microblaze_frame_cache cache;
 435
 436   /* This is the preferred method, find the end of the prologue by
 437      using the debugging information.  Debugging info does not always
 438      give the right answer since parameters are stored on stack after this.
 439      Always analyze the prologue.  */
 440   if (find_pc_partial_function (start_pc, NULL, &func_start, &func_end))
 441     {
 442       sal = find_pc_line (func_start, 0);
 443
 444       if (sal.end < func_end
 445           && start_pc <= sal.end)
 446         start_pc = sal.end;
 447     }
 448
 449   ostart_pc = microblaze_analyze_prologue (gdbarch, func_start, 0xffffffffUL,
 450                                            &cache);
 451
 452   if (ostart_pc > start_pc)
 453     return ostart_pc;
 454   return start_pc;
 455 }
 456
 457 /* Normal frames.  */
 458
 459 struct microblaze_frame_cache *
 460 microblaze_frame_cache (struct frame_info *next_frame, void **this_cache)
 461 {
 462   struct microblaze_frame_cache *cache;
 463   struct gdbarch *gdbarch = get_frame_arch (next_frame);
 464   CORE_ADDR func, pc, fp;
 465   int rn;
 466
 467   if (*this_cache)
 468     return *this_cache;
 469
 470   cache = microblaze_alloc_frame_cache ();
 471   *this_cache = cache;
 472   cache->saved_regs = trad_frame_alloc_saved_regs (next_frame);
 473
 474   /* Clear offsets to saved regs in frame.  */
 475   for (rn = 0; rn < gdbarch_num_regs (gdbarch); rn++)
 476     cache->register_offsets[rn] = -1;
 477
 478   func = get_frame_func (next_frame);
 479
 480   cache->pc = get_frame_address_in_block (next_frame);
 481
 482   return cache;
 483 }
 484
 485 static void
 486 microblaze_frame_this_id (struct frame_info *next_frame, void **this_cache,
 487                        struct frame_id *this_id)
 488 {
 489   struct microblaze_frame_cache *cache =
 490     microblaze_frame_cache (next_frame, this_cache);
 491
 492   /* This marks the outermost frame.  */
 493   if (cache->base == 0)
 494     return;
 495
 496   (*this_id) = frame_id_build (cache->base, cache->pc);
 497 }
 498
 499 static struct value *
 500 microblaze_frame_prev_register (struct frame_info *this_frame,
 501                                  void **this_cache, int regnum)
 502 {
 503   struct microblaze_frame_cache *cache =
 504     microblaze_frame_cache (this_frame, this_cache);
 505
 506   if (cache->frameless_p)
 507     {
 508       if (regnum == MICROBLAZE_PC_REGNUM)
 509         regnum = 15;
 510       if (regnum == MICROBLAZE_SP_REGNUM)
 511         regnum = 1;
 512       return trad_frame_get_prev_register (this_frame, cache->saved_regs, regnum);
 513     }
 514   else
 515     return trad_frame_get_prev_register (this_frame, cache->saved_regs,
 516                                          regnum);
 517
 518 }
 519
 520 static const struct frame_unwind microblaze_frame_unwind =
 521 {
 522   NORMAL_FRAME,
 523   microblaze_frame_this_id,
 524   microblaze_frame_prev_register,
 525   NULL,
 526   default_frame_sniffer
 527 };
 528 \f
 529 static CORE_ADDR
 530 microblaze_frame_base_address (struct frame_info *next_frame, void **this_cache)
 531 {
 532   struct microblaze_frame_cache *cache =
 533     microblaze_frame_cache (next_frame, this_cache);
 534
 535   return cache->base;
 536 }
 537
 538 static const struct frame_base microblaze_frame_base =
 539 {
 540   &microblaze_frame_unwind,
 541   microblaze_frame_base_address,
 542   microblaze_frame_base_address,
 543   microblaze_frame_base_address
 544 };
 545 \f
 546 /* Extract from an array REGBUF containing the (raw) register state, a
 547    function return value of TYPE, and copy that into VALBUF.  */
 548 static void
 549 microblaze_extract_return_value (struct type *type, struct regcache *regcache,
 550                                  gdb_byte *valbuf)
 551 {
 552   gdb_byte buf[8];
 553
 554   /* Copy the return value (starting) in RETVAL_REGNUM to VALBUF.  */
 555   switch (TYPE_LENGTH (type))
 556     {
 557       case 1:   /* return last byte in the register.  */
 558         regcache_cooked_read (regcache, MICROBLAZE_RETVAL_REGNUM, buf);
 559         memcpy(valbuf, buf + MICROBLAZE_REGISTER_SIZE - 1, 1);
 560         return;
 561       case 2:   /* return last 2 bytes in register.  */
 562         memcpy(valbuf, buf + MICROBLAZE_REGISTER_SIZE - 2, 2);
 563         return;
 564       case 4:   /* for sizes 4 or 8, copy the required length.  */
 565       case 8:
 566         regcache_cooked_read (regcache, MICROBLAZE_RETVAL_REGNUM, buf);
 567         regcache_cooked_read (regcache, MICROBLAZE_RETVAL_REGNUM+1, buf+4);
 568         memcpy (valbuf, buf, TYPE_LENGTH (type));
 569         return;
 570       default:
 571         internal_error (__FILE__, __LINE__,
 572                         _("Unsupported return value size requested"));
 573     }
 574 }
 575
 576 /* Store the return value in VALBUF (of type TYPE) where the caller
 577    expects to see it.
 578
 579    Integers up to four bytes are stored in r3.
 580
 581    Longs are stored in r3 (most significant word) and r4 (least
 582    significant word).
 583
 584    Small structures are always returned on stack.
 585 */
 586
 587 static void
 588 microblaze_store_return_value (struct type *type, struct regcache *regcache,
 589                                const gdb_byte *valbuf)
 590 {
 591   int len = TYPE_LENGTH (type);
 592   gdb_byte buf[8];
 593
 594   memset (buf, 0, sizeof(buf));
 595
 596   /* Integral and pointer return values.  */
 597
 598   if (len > 4)
 599     {
 600        gdb_assert (len == 8);
 601        memcpy (buf, valbuf, 8);
 602        regcache_cooked_write (regcache, MICROBLAZE_RETVAL_REGNUM+1, buf + 4);
 603     }
 604   else
 605     /* ??? Do we need to do any sign-extension here?  */
 606     memcpy (buf + 4 - len, valbuf, len);
 607
 608   regcache_cooked_write (regcache, MICROBLAZE_RETVAL_REGNUM, buf);
 609 }
 610
 611 static enum return_value_convention
 612 microblaze_return_value (struct gdbarch *gdbarch, struct type *func_type,
 613                          struct type *type, struct regcache *regcache,
 614                          gdb_byte *readbuf, const gdb_byte *writebuf)
 615 {
 616   if (readbuf)
 617     microblaze_extract_return_value (type, regcache, readbuf);
 618   if (writebuf)
 619     microblaze_store_return_value (type, regcache, writebuf);
 620
 621   return RETURN_VALUE_REGISTER_CONVENTION;
 622 }
 623
 624 static int
 625 microblaze_stabs_argument_has_addr (struct gdbarch *gdbarch, struct type *type)
 626 {
 627   return (TYPE_LENGTH (type) == 16);
 628 }
 629
 630 static void
 631 microblaze_write_pc (struct regcache *regcache, CORE_ADDR pc)
 632 {
 633   regcache_cooked_write_unsigned (regcache, MICROBLAZE_PC_REGNUM, pc);
 634 }
 635 \f
 636 static int dwarf2_to_reg_map[78] =
 637 { 0  /* r0  */,   1  /* r1  */,   2  /* r2  */,   3  /* r3  */,  /*  0- 3 */
 638   4  /* r4  */,   5  /* r5  */,   6  /* r6  */,   7  /* r7  */,  /*  4- 7 */
 639   8  /* r8  */,   9  /* r9  */,  10  /* r10 */,  11  /* r11 */,  /*  8-11 */
 640   12 /* r12 */,  13  /* r13 */,  14  /* r14 */,  15  /* r15 */,  /* 12-15 */
 641   16 /* r16 */,  17  /* r17 */,  18  /* r18 */,  19  /* r19 */,  /* 16-19 */
 642   20 /* r20 */,  21  /* r21 */,  22  /* r22 */,  23  /* r23 */,  /* 20-23 */
 643   24 /* r24 */,  25  /* r25 */,  26  /* r26 */,  27  /* r27 */,  /* 24-25 */
 644   28 /* r28 */,  29  /* r29 */,  30  /* r30 */,  31  /* r31 */,  /* 28-31 */
 645   -1 /* $f0 */,  -1  /* $f1 */,  -1  /* $f2 */,  -1  /* $f3 */,  /* 32-35 */
 646   -1 /* $f4 */,  -1  /* $f5 */,  -1  /* $f6 */,  -1  /* $f7 */,  /* 36-39 */
 647   -1 /* $f8 */,  -1  /* $f9 */,  -1  /* $f10 */, -1  /* $f11 */, /* 40-43 */
 648   -1 /* $f12 */, -1  /* $f13 */, -1  /* $f14 */, -1  /* $f15 */, /* 44-47 */
 649   -1 /* $f16 */, -1  /* $f17 */, -1  /* $f18 */, -1  /* $f19 */, /* 48-51 */
 650   -1 /* $f20 */, -1  /* $f21 */, -1  /* $f22 */, -1  /* $f23 */, /* 52-55 */
 651   -1 /* $f24 */, -1  /* $f25 */, -1  /* $f26 */, -1  /* $f27 */, /* 56-59 */
 652   -1 /* $f28 */, -1  /* $f29 */, -1  /* $f30 */, -1  /* $f31 */, /* 60-63 */
 653   -1 /* hi   */, -1  /* lo   */, -1  /* accum*/, 33  /* rmsr */, /* 64-67 */
 654   -1 /* $fcc1*/, -1  /* $fcc2*/, -1  /* $fcc3*/, -1  /* $fcc4*/, /* 68-71 */
 655   -1 /* $fcc5*/, -1  /* $fcc6*/, -1  /* $fcc7*/, -1  /* $ap  */, /* 72-75 */
 656   -1 /* $rap */, -1  /* $frp */                                  /* 76-77 */
 657 };
 658
 659 static int
 660 microblaze_dwarf2_reg_to_regnum (struct gdbarch *gdbarch, int reg)
 661 {
 662   gdb_assert (reg < sizeof (dwarf2_to_reg_map));
 663   return dwarf2_to_reg_map[reg];
 664 }
 665
 666 static struct gdbarch *
 667 microblaze_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
 668 {
 669   struct gdbarch_tdep *tdep;
 670   struct gdbarch *gdbarch;
 671
 672   /* If there is already a candidate, use it.  */
 673   arches = gdbarch_list_lookup_by_info (arches, &info);
 674   if (arches != NULL)
 675     return arches->gdbarch;
 676
 677   /* Allocate space for the new architecture.  */
 678   tdep = XMALLOC (struct gdbarch_tdep);
 679   gdbarch = gdbarch_alloc (&info, tdep);
 680
 681   set_gdbarch_long_double_bit (gdbarch, 128);
 682
 683   set_gdbarch_num_regs (gdbarch, MICROBLAZE_NUM_REGS);
 684   set_gdbarch_register_name (gdbarch, microblaze_register_name);
 685   set_gdbarch_register_type (gdbarch, microblaze_register_type);
 686
 687   /* Register numbers of various important registers.  */
 688   set_gdbarch_sp_regnum (gdbarch, MICROBLAZE_SP_REGNUM);
 689   set_gdbarch_pc_regnum (gdbarch, MICROBLAZE_PC_REGNUM);
 690
 691   /* Map Dwarf2 registers to GDB registers.  */
 692   set_gdbarch_dwarf2_reg_to_regnum (gdbarch, microblaze_dwarf2_reg_to_regnum);
 693
 694   /* Call dummy code.  */
 695   set_gdbarch_call_dummy_location (gdbarch, ON_STACK);
 696   set_gdbarch_push_dummy_code (gdbarch, microblaze_push_dummy_code);
 697   set_gdbarch_push_dummy_call (gdbarch, microblaze_push_dummy_call);
 698
 699   set_gdbarch_return_value (gdbarch, microblaze_return_value);
 700   set_gdbarch_stabs_argument_has_addr
 701     (gdbarch, microblaze_stabs_argument_has_addr);
 702
 703   set_gdbarch_skip_prologue (gdbarch, microblaze_skip_prologue);
 704
 705   /* Stack grows downward.  */
 706   set_gdbarch_inner_than (gdbarch, core_addr_lessthan);
 707
 708   set_gdbarch_breakpoint_from_pc (gdbarch, microblaze_breakpoint_from_pc);
 709
 710   set_gdbarch_frame_args_skip (gdbarch, 8);
 711
 712   set_gdbarch_print_insn (gdbarch, print_insn_microblaze);
 713
 714   set_gdbarch_write_pc (gdbarch, microblaze_write_pc);
 715
 716   set_gdbarch_unwind_pc (gdbarch, microblaze_unwind_pc);
 717
 718   frame_base_set_default (gdbarch, &microblaze_frame_base);
 719
 720   /* Hook in ABI-specific overrides, if they have been registered.  */
 721   gdbarch_init_osabi (info, gdbarch);
 722
 723   /* Unwind the frame. */
 724   dwarf2_append_unwinders (gdbarch);
 725   frame_unwind_append_unwinder (gdbarch, &microblaze_frame_unwind);
 726   frame_base_append_sniffer (gdbarch, dwarf2_frame_base_sniffer);
 727
 728   return gdbarch;
 729 }
 730
 731 /* Provide a prototype to silence -Wmissing-prototypes.  */
 732 void _initialize_microblaze_tdep (void);
 733
 734 void
 735 _initialize_microblaze_tdep (void)
 736 {
 737   register_gdbarch_init (bfd_arch_microblaze, microblaze_gdbarch_init);
 738
 739   /* Debug this files internals.  */
 740   add_setshow_zinteger_cmd ("microblaze", class_maintenance,
 741                             &microblaze_debug_flag, _("\
 742 Set microblaze debugging."), _("\
 743 Show microblaze debugging."), _("\
 744 When non-zero, microblaze specific debugging is enabled."),
 745                             NULL,
 746                             NULL,
 747                             &setdebuglist, &showdebuglist);
 748
 749 }